Asphalt and method of producing the same



Sept- 11, 1956 H. L. BEDELL ET AL 2,762,757

ASPHALT AND METHOD OF PRODUCING THE SAME Filed Deo. 17, 1952 Legg? yoilsfrom the crude.

United States Patent() This invention has to do with asphalts and with amethod for producing the same.

In recent years, asphalts possessing a particular combination ofproperties have been developed for many specialty applications, such aspaper saturants in the paper art. These asphalts are characterized by alow viscosity with a large change in viscosity on heating, good thermalstability, and dryness at any given point. 'Ihey are generally referredto as cracked or synthetic, asphalts inasmuch as they are prepared bythermal cracking of gas oil stocks.

So advantageous are these cracked or synthetic asphalts that demand hasfar exceeded supply. n To meet 4.

this demand, attention has been focused upon other more availablehydrocarbon stocks as replacements for the stocks from which syntheticasphalts are usually produced. However, such other stocks as are insupply have not responded to the same thermal cracking operations -toyield the desired products.

It is an object of this invention, therefore, to provide a new methodfor preparing asphaltshaving the properties of cracked or syntheticasphalts. It is also an object to provide a method for preparing thedesired as` ph'alts from hydrocarbon stocks of conventional residualasphalts, which hydrocarbon stocks are in good supply and are relativelyinexpensive. Other objects and advantages of the invention will beappa-rent from the following description.

It has now been found that outstanding asphalts, comparable to crackedor synthetic asphalts, can be prepared from straight run asphalts by aparticular sequence of operations. A straight run asphalt is blendedwith a cyclic gas oil of low aniline number, the blend is then subjectedto Ia heat treatment or cracking operation and the product thus obtainedis thereafter reduced to provide the desired asphalt product. f

As indicated above, the particular sequence of operations which makespossible production of the desired asphalts of this invention is: l

( l) Blending a straight run asphalt with a regulated quantity of acyclic gas oil of a refractory nature,

a desired asphalt quality, and y (3) Reducing the heat treated orcracked asphalt of desired character.

Ycharge can be, broadly, any petroleum residuum or flux which remainsfollowing the separation of the volatile The separation of thesevolatile oils can be accomplished by `means of vacuumA distillation,

Vsteam distillation or by propane deasphalting. For exblend to an I .(2)Heat treating or cracking the blend, formed in (1) to l 2,762,757Patented Sept.-1-1, 1956 ample, resid-ua from Penn'sylvanan,Mid-Continental, Californian, Mid-East, Near East, Venezuelan, etc.crudes can be used. Or, in other words, residua from parainic,naphthenic, aromatic, high-sulfur stocks, etc.. are suitable. It will berecognized, of course, that ditte-fences in chargel stocks are reilectedin differences in character of the final products contemplated herein.Thefollowing analyses are typical of the asphalt charge stocks found tobe advantageous: t

Soft point, ring and ball, F

Speciic gravity 1.01-1.03

Penetra-tion:

@32 F., 200 g., 60 secs 5-13 if @77 F., 100 g., 5 secs 20-50 @115 F., 50g., 5 secs 70-175 Viscosity, Fu-ro'l, secs.:

@.275l F 30e-80o The gas oils used herein are cyclic in character, andare resistant to thermal cracking. Gas oils of this character are wellknown in the art as refractory stocks. They are generally prepared bycatalytic or thermal cracking processes :such as typified by theThermofor Catalytic Cracking (TCC) process or thermal crackingprocesses. Representative cyclic gas oil-s are the following oilsdesignated A and B:

Oil A Oil B Aromatics, Percent by wt 25 Unsaturates, Percent by Wt 59API Gravity. 7. 0 22. 3 Aniline Number 90 174 Pour Point +80 +85 Flash.F 380 365 Distillation, 5F.:

Sulfur 1. 4

Hydrogen to Carbon Ratio 9. 4 7. 5

Kinematie Viscosity (eentistokes):

@100 F 117. 0 1G. 15 @210 F 11. 4 3.33

`from oil B are not so desirable as asphalts produced from oil A. Itwill be noted that oil B is less cyclic or aromatic in character thanAis oil A. It is concluded, therefore, that oils having less aromaticity(indicated by higher aniline numbers) than oil B are not suitable in theprocess of this invention.

'Theproportions of the asphalt charge and gas oil can be variedconsiderably Within certain limits, depending uponV the source of theasphalt charge and upon the refractory naturerof the gas oil. Ingeneral, however, from about 10 to O 'per lcent by weight is made up ofthe asphalt'charge, with the balance gas oil. By way of illustration, avacuum reduced straight run asphalt, having a ring and ball soft pointof 13G-150 F., is used advantagcously in amounts of 20-30 per cent, byweight, with 80-70 per cent of a gas oil such as the oil identified asA, hereinabove.

As contemplated herein, heat treatment or cracking of the asphalt gasoil blend is conducted in the liquid phase under selected conditions oftemperature and time. In general, temperatures of the order of 875 to900 F. with time intervals of ve to three minutes are used; that is, thelower temperatures generally require the longer time intervals. Undersuch conditions as the foregoing, the resulting asphalt becomes innature similar to the synthetic asphalts.

Following the asphalt conversion or cracking operation, the productobtained hereby is reduced at a maximum temperature of about 800 F. Thisis advantageously accomplished by distillation, with vacuum or withsteam. For example, the heat modied or cracked product may be separatedinto overhead distillate and asphalt residue by vacuum or steamdistillation.

The conditions of reduction to asphalt do not have any eiect on thebasic properties of the asphalt. The asphalt properties are Xed by theprevious heat treatment and the composition of the blend treated. Thereduction is merely a means of separating out the asphalt from the otherproducts of the heat treated blend.

A typical operation contemplated herein is illustrated by the ilow sheetshown in the attached drawing. A blend of cyclic gas oil and asphaltcharge is pumped from charge blend tank 1 through line 2, by means ofpump 3, to preheater 4, through line 5.

The blend is passed through line 6, positioned in the central portion ofpreheater 4, where the oil is heated to about 750 F,

The heated blend is removed from the prehcater 4 through line 7 and isled into the upper portion of a cracking furnace 8. The blend flowsthrough the furnace (8) via line 9, and leaves the furnace at abou-t850- 900 F. via line 10. The heat treated or cracked product in line 10is then led through the pressure relief valve (11). From the pressurerelief valve, the product goes through line 10 to conventional vacuumdistillation equipment and is thereby separated into overhead distillateand asphalt bottoms.

Oils A and B were each blended with twenty per cent by weight of 140soft point, straight run asphalt (C) and heat treated as indicatedbelow:

Analysis of the straight run asphalt (C) before processing is recitedbelow:

Soft point, F 144 Sp. Gr. 77/77 1.017 Penetration 100-5-77 28 Xyleneequivalent Ductility cm. 77

4 Viscosity (centipoises):

350'F 176 325 F 310 300 F 584 275 F 1210 250 F 2640 Viscositytemperature susceptibility 0.733

From the foregoing results and analysis, it will be -noted that thecharge of Oil A and straight run asphalt (C) is converted to an asphalthaving properties corresponding to those of synthetic asphalts. Thecharge of Oil B and (C) is also converted to a modied asphalt. Again, itis emphasized that Oil B has a higher aniline number than Oil A,indicative of lesser aromaticity, and that the greater the aromaticcharacter of the charge oil the more desirable is the final product.

Tabulated below are data obtained by treating two blends of Oil A andthe straight -run asphalt (C). The blends were heat treated undersimilar conditions and then reduced to asphalts of the 140 soft pointrange.

66.6% Oil Oil A with A With 33.4% 20% Asphalt C Asphalt C Furnace OutletTemp., F 875 890 Soaking Factor 0. 15 0.19 Analysis of ResultingAsphalt:

Sp. Gr., 77/77 1. 0768 1.1214 Soft Point, F. 142 143 Flash, COC, F...530 480 Penetration, -5-7 18 9 Xylene Equivalent 75-80 90-95 SolubilityCCl4 99. 76 98. 84 Ductility (3l-67 0-196-l- Viscosity (eentipoiscs):

@350 F 66 48 7 85 216 173 355 375 50 F 1,010 918 Viscosity TemperatureSusceptibility 0, 841 0. 946

The data tabulated immediately above reveal that the greater thequantity of cyclic gas oil charge, the greater the modiiication of theasphalt charge. However, there is a practical or economical limit to thequantity of gas oil which can be used in the charge, since the largerquantity lof the gas oil increases the quantity of oil processed for theamount of modied asphalt produced.

Additional data is presented below in order to demonstrate the influenceof heat treating or cracking conditions upion the iinal product. In eachof the Runs given below, a blend comprising two parts of Oil A and onepart of the straight run asphalt (C) was used.

Run No 1 2 3 Processing Temp., F 815 875 905 Soaking Factor 0. 01710.1514 0. 3192 Analysis of Resulting Asphalt:

Soft Point, F 144 142 144 Penetration, 100-5-77 25 1S 13 Flash, F 530535 Solubility CCl4 99. 7G 95. 75 Xylene Equivalent 75-80 100+Ductility, 5 em. 77. 61-67 38-42 S. E. Viscosity (C. P.):

@400 F 60 @375 F 96 @350 F 157 66 68 @325 F- 275 127 108 @300 F- 570 216215 @275 F 355 700 @250 F 1,010 1, 200 Viscosity TemperatureSusceptibility 0. 683 0.841 0.876 oft Point-Penetration Index 05 -L 8'1. 2 Ductility Coefficient 3. 42 4. 0 4. 22

From the results directly above, it is concluded that the soaking factormaintained in Run l is too mild to provide the desired result. Thecharacter of asphalt arcanes? product of Run l is only slightly dilerentfrom the character of the straight run asphalt of the charge. Theasphalt product of Run 2 has desirable properties, thereby indicatingthat the heat treatment was suitable. In Run 3, the conditions ofoperation are approaching the upper limit of severity inasmuch as theSolubility CC14 value indicates the presence of some coke-like materialin the product.

In general, the products of this invention are characterized by thefollowing properties:

Broad Preferred Range Range Soft Point, 120 to 170 130 to 150 Sp. Gr.,77/77 1. 04 to 1. 20 1.08 to 1.16 Penetration: 100 gms., 5 secs., 77 F 0to 35 5 to 20 Xylene Equivalent 5 to 100-|- 60 to 100+ Ductilty 77 F 0to 100+ 40 to 100+ Solubility (C014) 95. 0 to 100 98.0 to 100 Viscosityin Centipoises:

250 F. 600 to 1, 000 275 F 200 to 400 300 F 100 to 200 325: F gotg 1go()350 F 0 lscosi y empara ure uscep i 1 y V' 't T t S t'bil't (Z50-350 F.)0.78 to 1. 2 0.9 to 1. 0

Typical uses to which the `asphalt products lof this invention can beput are the following: water-proong of paper; size or coating forinsulation board; saturant for panel and molding boards made from Kraftpaper; emulsions for briquetting of coal; preparation of moldingcompounds; saturant or binder for rock wool or liber glass; forcompounding with resins, such as vinsol resins.

The gas oils recovered with the asphalt products are also ofconsiderable value. They are used as rubber softeners, saturants forfelt and papers, resin plasticizers, etc. and fuels.

We claim:

1. The process for producing a synthetic modified asphalt, characterizedby a low viscosity with a large change in viscosity on heating, and goodthermal stability which comprises: heat treating at a temperature fromabout 850 F. to about 900 F. for a period of time from about fiveminutes to about three minutes, a blend of a straight run asphalt and ofa cyclic gas oil, said blend comprising from about ten to about fortyweight per cent of said straight run asphalt; and reducing the productobtained by said heat treatment, whereby said modied asphalt isobtained.

2. The process dened by claim 1 wherein the cyclic gas oil containsabout twenty-tive per cent by weight of aromatcs.

3. The process defined by claim 1 wherein the straight run asphalt has aring and ball soft point F.) from about to about 150.

4. The process defined by claim 1 wherein a soaking factor from about0.1 to about 0.35 is maintained in said heat treatment.

References Cited in the le of this patent UNITED STATES PATENTS1,881,753 Loebel Oct. 11, 1932 2,542,608 Winkler Feb. 20, 1951 2,658,857Roediger Nov. 10, 1953 2,662,051 Pelzer Dec. 8, 1953

1. THE PROCESS FOR PRODUCING A SYNTHETIC MODIFIED ASPHALT, CHARACTERIZEDBY A LOW VISCOSITY WITH A LARGE CHANGE IN VISCOSITY ON HEATING, A GOODTHERMAL STABILITY WHICH COMPRISES: HEAT TREATING AT A TEMPERATURE FROMABOUT 850* F. TO ABOUT 900* F. FOR A PERIOD OF TIME FROM ABOUT FIVEMINUTES TO ABOUT THREE MINUTES, A BLEND OF A STRAIGHT RUN ASPHALT AND OFA CYCLIC GAS OIL, SAID BLEND COMPRISING FROM ABOUT TEN TO ABOUT FORTYWEIGHT PER CENT OF SAID STRAIGHT RUN ASPHALT; AND REDUCING THE PRODUCTOBTAINED BY SAID HEAT TREATMENT, WHEREBY SAID MODIFIED ASPHALT ISOBTAINED.